MOTM

A lot of this discussion seems to center on the idea of using a VCO 
generated sawtooth wave, putting it into an A to D converter and using the 
output essentially as a counter.  The accuracy of this particular scheme is 
highly dependent on the sawtooth ramp being a perfectly straight line.  Any 
curvature in the ramp would cause the counter to count faster at some times 
and slower at others as the slope varies.

A better way would be to start with the triangle wave, run it through a 
series of rectifiers followed by capacitors to eliminate the DC component. 
This would get you a frequency multiplied triangle wave.  If you then 
generate a pulse from the frequency multiplied triangle you can drive a 
counter directly.  The result should be more linear than the sawtooth 
driving the A to D and you don't need a converter.

I would think you could run at least 8 rectifier/capacitor units in series. 
That would get you a 256x pulse.  You'd probably want to use high speed ops. 
I'd like to see a frequency multiplied module using this idea.  You could 
probably get some strange outputs by running complex waveforms in the input 
in place of a triangle.

Paul H.




----- Original Message ----- 
From: "jfm3" <jfm3@...>
To: "MOTM litserv" <motm@yahoogroups.com>
Sent: Monday, January 02, 2006 12:31 AM
Subject: Re: [motm] Interest in a MOTM-102 module?


> On Thu, 2005-12-29 at 09:59 -0500, Richard Brewster wrote:
>> This may be asking for a lot, but could it have a scale quantizer?  It
>> is digital to begin with.  How much extra would adding a major/minor
>> scale be?  How about a 3-position toggle switch:  major/minor/off.
>
> I've been thinking a lot about how to do pitch CV quantizing.  Being as
> it is the case that I'm new to the analog modular, and far more trained
> in software engineering than hardware, I probably have some of this
> wrong, so I ask that you forgive me for that, and take what I say
> without much authority.
>
> For my purposes, pre-programmed scales would be useless.  The long
> duration accuracy being discussed deeper in this thread turns me off
> too.  What I've decided I really want is a VC sequencer that steps
> through it's stages not once every time a square CV drops, but smoothly
> as a saw shaped CV goes from zero all the way up.  A triangle CV would
> make the sequencer go back and forth, etc..  With one of these, you
> could quantize pitch CVs into whatever other arbitrary set of pitch CVs
> you wanted.
>
> I think the Milton sequencer can do this.  I'm not sure how stable a
> Milton can hold it's output CV over time.  It also seems like the CV out
> of the Milton is digital, and it's not clear to me what resolution that
> has.  I have some Milton boards and preprogrammed PICs, but getting
> front panels and stuffing the boards properly is a little daunting given
> that I don't really completely know what I'm doing.
>
> What's the output CV resolution on the Miniwave, and can you still get
> them?
>
> (jfm3)
>
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